General approach and scope

This paper describes a joint activity involving NASA and Army researchers at the NASA Langley Research Center to develop optimization procedures aimed at improving the rotor blade design process by integrating appropriate disciplines and accounting for all of the important interactions among the disciplines. The disciplines involved include rotor aerodynamics, rotor dynamics, rotor structures, airframe dynamics, and acoustics. The work is focused on combining these five key disciplines in an optimization procedure capable of designing a rotor system to satisfy multidisciplinary design requirements. Fundamental to the plan is a three-phased approach. In phase 1, the disciplines of blade dynamics, blade aerodynamics, and blade structure will be closely coupled, while acoustics and airframe dynamics will be decoupled and be accounted for as effective constraints on the design for the first three disciplines. In phase 2, acoustics is to be integrated with the first three disciplines. Finally, in phase 3, airframe dynamics will be fully integrated with the other four disciplines. This paper deals with details of the phase 1 approach and includes details of the optimization formulation, design variables, constraints, and objective function, as well as details of discipline interactions, analysis methods, and methods for validating the procedure

An initiative in multidisciplinary optimization of rotorcraft

Described is a joint NASA/Army initiative at the Langley Research Center to develop optimization procedures aimed at improving the rotor blade design process by integrating appropriate disciplines and accounting for important interactions among the disciplines. The activity is being guided by a Steering Committee made up of key NASA and Army researchers and managers. The committee, which has been named IRASC (Integrated Rotorcraft Analysis Steering Committee), has defined two principal foci for the activity: a white paper which sets forth the goals and plans of the effort; and a rotor design project which will validate the basic constituents, as well as the overall design methodology for multidisciplinary optimization. The optimization formulation is described in terms of the objective function, design variables, and constraints. Additionally, some of the analysis aspects are discussed and an initial attempt at defining the interdisciplinary couplings is summarized. At this writing, some significant progress has been made, principally in the areas of single discipline optimization. Results are given which represent accomplishments in rotor aerodynamic performance optimization for minimum hover horsepower, rotor dynamic optimization for vibration reduction, and rotor structural optimization for minimum weight

Integrated multidisciplinary design optimization of rotorcraft

The NASA/Army research plan for developing the logic elements for helicopter rotor design optimization by integrating appropriate disciplines and accounting for important interactions among the disciplines is discussed. The optimization formulation is described in terms of the objective function, design variables, and constraints. The analysis aspects are discussed, and an initial effort at defining the interdisciplinary coupling is summarized. Results are presented on the achievements made in the rotor dynamic optimization for vibration reduction, rotor structural optimization for minimum weight, and integrated aerodynamic load/dynamics optimization for minimum vibration and weight

Integrated multidisciplinary optimization of rotorcraft: A plan for development

This paper describes a joint NASA/Army initiative at the Langley Research Center to develop optimization procedures aimed at improving the rotor blade design process by integrating appropriate disciplines and accounting for important interactions among the disciplines. The paper describes the optimization formulation in terms of the objective function, design variables, and constraints. Additionally, some of the analysis aspects are discussed, validation strategies are described, and an initial attempt at defining the interdisciplinary couplings is summarized. At this writing, significant progress has been made, principally in the areas of single discipline optimization. Accomplishments are described in areas of rotor aerodynamic performance optimization for minimum hover horsepower, rotor dynamic optimization for vibration reduction, and rotor structural optimization for minimum weight

An initiative in multidisciplinary optimization of rotorcraft

Described is a joint NASA/Army initiative at the Langley Research Center to develop optimization procedures aimed at improving the rotor blade design process by integrating appropriate disciplines and accounting for important interactions among the disciplines. The activity is being guided by a Steering Committee made up of key NASA and Army researchers and managers. The committee, which has been named IRASC (Integrated Rotorcraft Analysis Steering Committee), has defined two principal foci for the activity: a white paper which sets forth the goals and plans of the effort; and a rotor design project which will validate the basic constituents, as well as the overall design methodology for multidisciplinary optimization. The paper describes the optimization formulation in terms of the objective function, design variables, and constraints. Additionally, some of the analysis aspects are discussed and an initial attempt at defining the interdisciplinary couplings is summarized. At this writing, some significant progress has been made, principally in the areas of single discipline optimization. Results are given which represent accomplishments in rotor aerodynamic performance optimization for minimum hover horsepower, rotor dynamic optimization for vibration reduction, and rotor structural optimization for minimum weight

Off-Farm Work By Census-Farm Operators: An Overview of Structure and Mobility Patterns

The purpose of this paper is to provide descriptive statistics on off-farm labour supply and farm/off-farm labour reallocation for Canadian farmers using cross-sectional data and cross-sectional panel data, respectively, obtained from the Canadian Census of Agriculture. This report is part of a larger study on the off-farm labour supply and labour mobility of farm operators (Swidinsky, 1997). The data indicates that a growing proportion of operators worked off-farm between 1971 and 1991. As well, operators who work off-farm have allocated greater amounts of time to the off-farm labour market. The share of census-farm operators reporting 97-228 days of off-farm work has risen from 11 percent to 15 percent, while the share working more than 228 days off-farm has increased from 13 percent to 16 percent of all operators from 1971 to 1991. There is also some mobility between the status of full-time and part-time farming, but a high proportion of both types of operators exit farming over a five-year period. Less than 15 percent of operators farming full-time change to part-time, while approximately 20 percent of operators farming full-time change to part-time. In contrast, approximately 25 percent of full-time operators exit farming, while 35 percent of part-time operators exit farming over a typical five-year period.Labor and Human Capital,

Rotor blade dynamic design

The rotor dynamic design considerations are essentially limitations on the vibratory response of the blades which in turn limit the dynamic excitation of the fuselage by forces and moments transmitted to the hub. Quantities which are associated with the blade response and which are subject to design constraints are discussed. These include blade frequencies, vertical and inplane hub shear, rolling and pitching moments, and aeroelastic stability margin

Estimating the Off-farm Labor Supply in Canada

Off-farm labor supply in Canada is modeled using separate off-farm labor participation and off-farm labor supply equations, which allows variables to affect participation and labor supply differently. The data used in this study are from Statistics Canada’s Agriculture-Population Linkage Database, which links the Population Census for 1986 to a 20% sample from the Census of Agriculture. Results indicate that age, education and wages have large, significant and opposite effects on participation and supply, and that government efforts to stabilize and supplement farm incomes through rural employment programs may have less effect on labor allocation decisions than do the underlying demographic factors and regional and farm characteristics

Healable polymeric materials: a tutorial review

Given the extensive use of polymers in the modern age with applications ranging from aerospace components to microcircuitry, the ability to regain the mechanical and physical characteristics of complex pristine materials after damage is an attractive proposition. This tutorial review focusses upon the key chemical concepts that have been successfully utilised in the design of healable polymeric materials

Ultrafiltration in the Ontario Dairy Industry

The economics of introducing ultrafiltration (UF) into the Ontario dairy industry is analyzed. First, a partial budget is developed to determine feasibility of UF on the farm. The budget indicates that the great majority of Ontario dairy farms are not large enough to capture the economies of size inherent in the new technology. Second, a location-allocation model is used to determine the feasibility, number and location of UF collection centers in Ontario. The model indicates that the UF centers would capture the economies of size and the centers would benefit the dairy industry as a whole. However, processors of soft products and consumers of hard products could be worse off because of market changes caused by the UF center